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Discussion Starter #1
My holding tank is fiberglass and its in the v-berth rght next to the bulkhead. All of the hoses go through the bulkhead into the under sink cabinet. from there they make thier way to the head or up to the to the pumpout fitting. There was a awful stank coming from that cabinet, and no where else. It seemed pretty clear that the older hoses had permeated. These hoses pre-dated me (well, pre-dated my ownership anyway) so they are 5 or more years old.

The pump out is plumbed to the bottom of the tank; no dip tube. So that means that except for a brief period after a pumpout, there is *always* standing sewage in that discharge hose.

This spring I rebuilt the head and replaced all of the hoses. I went to west marine and used the hose that they had on hand: SEALAND OdorSafe Plus Sanitation Hose | West Marine

I suspect this hose is not the best, perhaps not the worst either.

Last weekend when i got to the boat, i was greeted by that familiar stank. I checked and sure enough it was coming from the cabinet under the sink, through which all of my holding tank hoses pass.

I used the "warm rag" trick on the hoses and I'd say the result is inconclusive. but it is clear that the smell is coming from under the sink.

Could it be that the new hoses permeated in just a few months? Or could I have another, more sinister, issue going on?
 

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bell ringer
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having just done a full replace I have to ask, when you did the did you replace ALL the hoses including the vent hose?
 

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No, the Sealand hose could not have permeated that quickly. Testing suggests more than 5 years, but certainly at least 3-4.

I would suspect a very slow leak at a fitting. You could try wrapping the joints with aluminum tape, which is permeation-proof, just as a trouble shooting measure.
 

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Don't call me a "senior"!
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...
The pump out is plumbed to the bottom of the tank; no dip tube. So that means that except for a brief period after a pumpout, there is *always* standing sewage in that discharge hose.
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There's your problem. As long as you have a hose continually full of $hit, any fix that keeps the hoses in the current configuration is going to be a very temporary fix. If you want a long-term fix you'll have to replace the holding tank with one that empties from the top. Yes, that's probably a bigger job than you really want to do. But doing a job right is often a PITA. The question you have to ask is which PITA do you want: stinky hoses that are a perennial PITA and have to be changed on a regular basis, or the one-time PITA of redoing the system?
 

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Discussion Starter #5
having just done a full replace I have to ask, when you did the did you replace ALL the hoses including the vent hose?
Yes vent hose included.

You bring a good point. My vent is truly one sh*ty arrangement. in my original post I said that all hoses pass through the cabinet, but I forgot about the vent. It's 5/8in and trails all the way up to the bow to a tiny fitting. I'm certain that there are low spots along its nearly 10ft length. I cant imagine how this (small diameter, long length, probable low spots) could effectively vent the tank.
 

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I suspect this hose is not the best, perhaps not the worst either.
It's not the most highly recommended however it is one of the newer PVC hoses as opposed to the older (up to the 90's) rubber hoses. The older black rubber hoses were notorious for getting permeated rather quickly and the new white ones are supposed to be more resistant.
Even if you've replaced vent hose do check to make sure it or whatever type of "vent cap" it has been fitted with on the exterior has not become clogged.
 

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Discussion Starter #7
any fix that keeps the hoses in the current configuration is going to be a very temporary fix. If you want a long-term fix you'll have to replace the holding tank
agreed. With a new tank I'll be able to address the discharge and the vent issue.

Still I had hoped that new hoses would have bought me a bit longer than a few months.
 

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Don't call me a "senior"!
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agreed. With a new tank I'll be able to address the discharge and the vent issue.

Still I had hoped that new hoses would have bought me a bit longer than a few months.
When you put in the new tank install two vents, with their deck fittings on opposite sides of the deck (if possible). That way there will be a significant pressure differential between the two vents and therefor a significant flow of fresh air into the tank. A single vent only equalizes the pressure between the tank and the atmosphere; it does little or nothing to keep the tank aerobic. Two vents will help to keep the tank aerobic, and thus less stinky.
 
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bell ringer
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New hose I feel definitely should have lasted a LOT more than months. Are you sure the odor isn't in the locker walls themselves? Have you cleaned them well and sprayed with PureArye etc?
 

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Similar problem and replaced hoses. Still smelled it although not so bad. Took a long time for the smell to leave the wood and other stuff in the area where the bad hoses were.:eek:
 

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Even with the hoses full (that is how we tested them, obviously) you should get 5 years with that hose.

You have a leak or residual odor.
 

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Sealand hose is pretty good. We have it on our boat and it has 5 years use with no smells.
 

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There's your problem. As long as you have a hose continually full of $hit, any fix that keeps the hoses in the current configuration is going to be a very temporary fix. If you want a long-term fix you'll have to replace the holding tank with one that empties from the top. Yes, that's probably a bigger job than you really want to do. But doing a job right is often a PITA. The question you have to ask is which PITA do you want: stinky hoses that are a perennial PITA and have to be changed on a regular basis, or the one-time PITA of redoing the system?
This is not true at all about having to have a dip tube tank. When we redid our holding tank plumbing we placed a 1.5 inch PVC pipe with valve at the bottom of the tank which can be shut to prevent sewage from sitting in the hose until pump out time. The valve leads to a Y valve which either goes to the deck pumpout or mascerator then thru hull.

I am not a fan of dip tubes as they can get clogged. Plus this allows the natural weight and gravity of the liquid in the tank to help clear out the effluent .

Amazon.com: 1-1/2" PVC Ball Valve (Female Pipe X Female Pipe): Home [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@31NASoR1ovL

Dave
 

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When you put in the new tank install two vents, with their deck fittings on opposite sides of the deck (if possible). That way there will be a significant pressure differential between the two vents and therefor a significant flow of fresh air into the tank. A single vent only equalizes the pressure between the tank and the atmosphere; it does little or nothing to keep the tank aerobic. Two vents will help to keep the tank aerobic, and thus less stinky.
Two vents of sufficient size can be better, but our 1 - 1/2 inch vent hose has always been sufficient to aerate the tank an keep it aerobic.
 

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This is not true at all about having to have a dip tube tank. When we redid our holding tank plumbing we placed a 1.5 inch PVC pipe with valve at the bottom of the tank which can be shut to prevent sewage from sitting in the hose until pump out time. The valve leads to a Y valve which either goes to the deck pumpout or mascerator then thru hull.
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That is another way around the problem. However, it requires that one have access to the bottom of the tank so that the valve may be actuated. Such access is often difficult to come by without sacrificing a lot of space that could otherwise be used for tankage; and sometimes just difficult to come by, period. I've seen some boats with set-ups like you describe that seem to work. However, there is still the problem of tiny (and very stinky) leaks developing around the thru-hull fitting, at the joint(s) between the thru-hull and the valve, and within the valve itself. It doesn't take very many drops from the holding tank to make such a problem apparent. Also, if there is a clog (or some other problem) that necessitates taking the plumbing apart while the tank is full would you rather disassemble a valve/thru-hull/whatever that rests on the top of the waste tank (and has zero pressure on it, with nothing but some nasty fumes ready to vent when you break into the plumbing), or one that sits under said tank (and has 15, or 25, or more gallons of "black water" pushing against it, ready to gush out and spill all over the place)?

I've never had the dip-tube on my boat's holding tank clog to the point that I had to take things apart. The worst that has ever happened ahas been quickly cleared up by back flushing it for a few seconds with the water hose at the pump-out dock. Generally, clogs happen when anything other than human waste and single-ply TP gets flushed. Keep the stuff out of the waste tank that doesn't belong there and your chances of a serious clog will approach zero.
 
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Don't call me a "senior"!
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Two vents of sufficient size can be better, but our 1 - 1/2 inch vent hose has always been sufficient to aerate the tank an keep it aerobic.
If the vent hose is short enough this method should work fine. But once the hose gets to be more than a foot or two long the amount of exchange with the atmosphere is going to be pretty limited. With two vents, and smaller diameter tubing, one has a lot more options with respect to where to locate the vent deck fitting(s). The ones on my boat are located fairly high on the sides of the cabin, giving them plenty of breeze to move air in and out of the tank.
 

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That is another way around the problem. However, it requires that one have access to the bottom of the tank so that the valve may be actuated. Such access is often difficult to come by without sacrificing a lot of space that could otherwise be used for tankage; and sometimes just difficult to come by, period. I've seen some boats with set-ups like you describe that seem to work. However, there is still the problem of tiny (and very stinky) leaks developing around the thru-hull fitting, at the joint(s) between the thru-hull and the valve, and within the valve itself. It doesn't take very many drops from the holding tank to make such a problem apparent. Also, if there is a clog (or some other problem) that necessitates taking the plumbing apart while the tank is full would you rather disassemble a valve/thru-hull/whatever that rests on the top of the waste tank (and has zero pressure on it, with nothing but some nasty fumes ready to vent when you break into the plumbing), or one that sits under said tank (and has 15, or 25, or more gallons of "black water" pushing against it, ready to gush out and spill all over the place)?

I've never had the dip-tube on my boat's holding tank clog to the point that I had to take things apart. The worst that has ever happened ahas been quickly cleared up by back flushing it for a few seconds with the water hose at the pump-out dock. Generally, clogs happen when anything other than human waste and single-ply TP gets flushed. Keep the stuff out of the waste tank that doesn't belong there and your chances of a serious clog will approach zero.
My solution will work for most boats and doesn't require some narrow dip tube, but won't work for all. Dip tubes clog very frequently. We have an access port to get at the top of the tank, and working on the plumbing at the bottom of the tank has no pressure on it as the valve is shut.

Dip tubes do not pull all the sludge at the bottom of the tank out by their design. The heaviest sediment is left to "concretize" over time. Not so with a bottom valve.

All I pointed out was there us more than one solution. Not a correct one in this case.
 

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Did any prior hoses leak and put raw sewage into the bilge or bulkhead? As others have said, its not very likely that you have permeation already.

Does the waste line from the head go up to a vented loop first? Is that vent open? They often fail, although, I find they typically fail closed.

Another vote for replacing that vent line with at least 1" hose or you will never get enough air to keep your tank from stinking. Also, if I can only get the unfamiliar to do one thing with their marine heads, its to flush enough clear water to push all the effluent to the tank. That's usually at least one full gallon, after the waste is evacuated from the bowl.
 

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a. I don't understand the critisism of dip tubes, unless there is a maserator pump also mounted low. If the tank is to be vacuumed out, the dip tub will have exactly the same static head and perhaps less frictional loss. As for clogging, either can be a problem, though with proper use neither is a problem, and backflushing will solve both.

b. Big vents can work. Nitrate treatments work. And carbon vent filters work (>3 years). I've tested all 3 side-by-side. What does not work is a small vent, no treatment, veggy oil in the head, and too little flush water. This is generally the common mode when there are troubles, whether odor or clogging.
 

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Discussion Starter #20
Did any prior hoses leak and put raw sewage into the bilge or bulkhead? As others have said, its not very likely that you have permeation already.
luckily no leaks, and the bilge and bulk head compartments smell fresh. Its just the cabinet under the sink where all of the hoses pass. As others have said permeation of the cabinet itself or a leak at the joints seem most likely at this point.

Another vote for replacing that vent line with at least 1" hose or you will never get enough air to keep your tank from stinking.
agreed, I think the venting of this tank is completely ineffective. This will be remedied in the fall.

flush enough clear water to push all the effluent to the tank. That's usually at least one full gallon, after the waste is evacuated from the bowl.
A good point. I do flush a full gallon of clear water through the head anytime I leave the boat for more a few days.
 
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